tree 6c73be7204c9a454d9450a8a996417445b69cd06
parent 17ceaae16ef73fdc7dd77dba7e6820ac09134595
author Richard Patel <me@terorie.dev> 1764735676 -0600
committer GitHub <noreply@github.com> 1764735676 +0000
gpgsig -----BEGIN PGP SIGNATURE-----
 
 wsFcBAABCAAQBQJpL7q8CRC1aQ7uu5UhlAAAL9gQAGzs6D4V8VNTLLkPHx9v7IMr
 LwYTqN5+uQb91InIGuoA0yAMC0Dwj+yZfAT/ENwRq00j7z8riGDBoGeCowLjXjbo
 u8AFHCyjda2Z2OYrzt9dqFp20aIM/8sAhTPNtRfWEtLjV1JbPIR5rGVzwMgUIZfN
 mRQ38qEUqanV9/bPVSQxxgCEzfFUrztzeEU5KTScVb5kNJy7DgHn75uTKZL87VEg
 N/mPJA+RgLjRog/fDK+zoWX/xaHwS4fDiW4jKOtfJi0mAanGboQHFLKfknHbyqcp
 0Ys3/rViP6OS76RK7ysg8jJiWqcpEBx/N01nSN9iQlxNoEbObfiPdMVQ2iBNeCwR
 4w0aG0dFnhReEMxns84zhW6STAqwOTkXhveOVkgUO70pheDgTlHkq5mXHfXHhdwT
 h2GS1f3YxHFsWtUoFUvmix2qMK4vHjdq2BbK+XPb2ESrZO1Jy1IGGWKxF9AafT69
 NaIqdQm+XZZbKLyG1BPHSM+wRrytrtu2/FOgZ1UxQvLL/qPt/aLdxaRHJ0yUWPs+
 Ev/O9bz/VE9T+o96gDOfTnVrAQaPq1IgO5qYIEYQtNmYD9gUFe5IRY8tTJjO6JF3
 wghg0KNoNbdcTPuxqdfFyYH07BQqc0GIpgZg0nnsDP+FiM8AweFhOYTRiueeb9Bb
 yUMpC5ppnmXBZD7cfWRj
 =Ra0e
 -----END PGP SIGNATURE-----
 

rust: impl TrustedLen for VectorIter (#8797)

Improves unpack performance for vectors by allowing the compiler
to vectorize flatbuffers::Vector to std::vec::Vec conversions,
using the unstable trusted_len feature.

Internally, enables an optimization in src/alloc/vec/spec_extend.rs:
Previously, unpacking a flatbuffers::Vector called
SpecExtend::extend_desugared fallback, which inhibits vectorization
(due to a branch before every element move).  Declaring TrustedLen
allows SpecExtend::extend_trusted, which LLVM can often vectorize
into a memcpy.

For [ubyte] vectors in particular, this turns a rather expensive
loop of 'mov BYTE PTR [rax+r13*1], bpl' into a `call memcpy`.